In large buildings such as hotels and offices, it is often desirable to have the ability to alert the occupants of the building as to the existence of an emergency, and to provide each occupant with information such as evacuation instructions. One method of doing the same would be by a loudspeaker in each room to communicate an audible message to the occupant. Convenience and safety would dictate that the emergency message be transmitted to each room simultaneously.
There are many systems available for the transmission of emergency communications to the rooms of a building. Many such systems use the existing telephone lines as the link between a central paging system and the remote room. These systems are rather complicated and often times totally disable the phone system. Generally they employ rather involved hardware to generate the audio message and the necessary voltages to activate the particular system. And, it is not uncommon for such systems to require involved retrofitting to existing lines with the attendant cost for same. Of course there are other approaches that do not use the existing phone lines to convey the emergency traffic but they might require the added cost of a wireless link or additional hardwiring in the building.